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Is a t7 head a direct swap?

5K views 13 replies 6 participants last post by  StonePipes 
#1 ·
Will it just bolt on and be happy on a t5 block? I have read that the t5 cams are better. Hows about an N/A intake cam and turbo exhaust cam, would that be nice. A saab mechanic who is a family friend thinks my coolent leak is the head gasket so I was just wondering about the possibiltys wile the head was off when it gets repaired. I have a wile to think about it I hope anyway I am only putting in about a coffe mugs worth of coolent in the car with every fillup of gas.
 
#3 ·
T5 cams flow more than T7 cams. I know Maptun uses those as an upgrade for T7 cars. Only drawback to the T7 head that I see is the valve stems are smaller than the T5 head which is part of the reason the T7 heads flow better. Nick experimented with some N/A cams recently and I can't remember what he decided about them but remember that the N/A cames will probably be tuned for higher RPM where our turbo's need midrange flow to give us that torque we all love.

So unless you have some giant disco potatoe that can keep pushing huge amounts of air up top and not just really hot boosted air than T7 head and N/A cams might be a good setup. I can't say for certain but its plausible speculation. That is also assuming the N/A cams don't make turbo lag on a really big turbo even worse.

Otherwise stick with T7 head with T5 cams combination.
 
#4 ·
cams aside i'm not sure if a T7 head will be a simple bolt on with a T5 block because of differences in the manifolds between the two generations. I thinks its mostly the intake manifold that has different inlets comparted to a T5 engine.

although i'd probably take boxmans word over mine
 
#5 · (Edited)
boxman said:
you can bolt a T7 head to a T5 block but you need to use the T5 had gasket to keep the right compression ratio, as for cams i'm not sure there is a sure fire answer to this
Was the T7 head-gasket that much thinner, or thicker than T5? I'm guessing it's thinner and would make the compression ratio slightly too high? (I'm pretty sure the combustion chambers are the same volume.) Either way, head gaskets usually don't make up more than half a point in compression ratio, which would move the 2.0 from 8.8 either down to 8.3-8.7:1 ... or up to 8.9-9.3:1. None of which would be a bad thing under the right circumstances. The quench distance, on the other hand ...

The inlet ports could be bigger, but they look rather similar (both these pics are ported pics, but both used the stock manifold, so I doubt the opening was significantly altered and the interior was ported instead) The T7 inlet port does look slightly taller, especially where the fuel is injected:

T5 Ported slightly:


T7 Ported slightly:


The combustion chambers also look pretty similar (both have larger valves than stock):

T5 Combustion chamber:


T7 Combustion chamber(s):


So the debate continues ...
 
#6 · (Edited)
T7 engines have a alloy gasket and its very thin les than half the thickness as the standard gasket fitted to the T5 engine and the piston crowns are much deeper on the T7 engine


a T5 inlet manifold will not fit a T7 head, sorry i assumed the question was, can i use a T5 block in my T7 car :roll:
 
#7 ·
boxman said:
T7 engines have a alloy gasket and its very thin les than half the thickness as the standard gasket fitted to the T5 engine and the piston crowns are much deeper on the T7 engine
Well that would make sense in order to keep the compression ratio the same.

But even much thinner, the T5 gasket isn't THAT thick. With no gasket at all, I can't see it being more than about 9.3:1 CR on the 2.0. So even a very thin gasket shouldn't go much higher than that, right? :eek:

For stock-ish turbo 9.0-9.3:1 might even be kinda nice for better mileage, engine response, or even power, if you have high enough octane where you are. It's just when you get into really ginormous turbos ...

Not that I'm reccomending against the T5 gasket! I am curious if the alloy gasket is much stronger, though I doubt it since it's so thin, but by no means am I saying you should use it without checking the change in CR it would make! ;oops:

Here's a pic of a T7 head on the inlet side from afar, NOT ported:


Hmmmm ... maybe Viggen (non-LEV) intake manifold and someone's dead electronic throttle-body? (works like a normal one when the motor dies and has a cable) Or maybe the T5 intake manifold can be ported to the T7 port size? :confused:
 
#8 ·
boxman said:
a T5 inlet manifold will not fit a T7 head, sorry i assumed the question was, can i use a T5 block in my T7 car :roll:
Looks like just the gasket would be different and the ports slightly taller on the T7 head. Is it too much for the thickness of the T5 manifold to account for?

Or are the bolt hole locations actually sliiiiightly different? (they look the same)
 
#11 ·
Can the t5 intake be ported out? I would find it hard to believe that you would have to remove so much metal that the strength would be compromized, but maybe I am wrong. I was under the assumption that this was a common mod:confused: You guys are great! thanks for the info so far.
 
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